Built detergent composition containing whiteness maintenance additive

ABSTRACT

A BUILT DETERFENT COMPOSITION IS FORMULATED HAVING EXCELLENT WHITENESS MAINTENANCE PROPERTIES. THE BUILT DETERGENT COMPOSITION HAS INCLUDED THEREWITH FROM 0.1% TO 20% OF A MIXTURE OF THE WATER-SOLUBLE SALTS OF A CELLULOSE SULFATE ESTER AND A COPOLYMER OF A VINYL COMPOUMD AND MALEIC ANHYDRIDE, THE MIXTURE OF THE SULFATE ESTER AND COPOLYMER WHEN ADDED TO A BUILT DETERGENT COMPOSITION IMPROVES THE WHITENESS MAINTENANCE OF FABRICS WASHED THEREWITH OVER A BUILT DETERGENT COMPOSITION CONTAINING EITHER COMPONENT ALONE.

United States Patent O 3,794,605 BUILT DETERGENT COMPOSITION CONTAININGWHITENESS MAINTENANCE ADDITIVE Francis L. Diehl, Wyoming, Ohio, assignorto The Procter & Gamble Company, Cincinnati, Ohio N Drawing. Filed July19, 1971, Ser. No. 164,067

Int. Cl. Clld 3/34 U.S. Cl. 252-89 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION This invention relates to built detergentcompositions containing an additive which effectively prevents thedeposition of removed soil and hardness ion-builder salts or complexesformed during the laundering of textile fabrics. More particularly, thewhiteness maintenance of fabrics washed with the composition of thisinvention is improved.

The washing of soiled fabrics with a laundry detergent is essentially atwo-step process. In the first stage the detergent removes the soilparticles from the fabrics and suspends them in the wash solution. Inthe second stage the detergent must prevent the soil particles and otherinsolubles from redepositing on the cloth before the fabric is removedfrom the dirty soil solution or during the rinse cycles. The exactmechanism by which the second stage operates is not known. It istheorized that a charge is formed on the fabric being washed and thatthis charge repels the soil particles which carry a similar charge. Ifsoil particles once removed from the fabrics are allowed to redepositthereon the resultant fabrics once dried will have an uncleanappearance. This appearance can be traced directly to the redepositedsoil particles and can be measured quantitatively in terms of awhiteness value, as hereinafter explained. The amount of redepositedsoil particles as measured by the whiteness value is an indication ofthe whiteness maintenance property of a detergent composition.

Another factor that has an effect on the whiteness maintenance is thedeposition of water-insoluble hardness ion-builder salts or complexes onthe fabrics. This factor can be as important as the prevention of soilredeposition with regard to whiteness maintenance. The formation ofhardness ion-insoluble salts is most noticeable with detergentcompositions containing builders such as polymaleate, polyacrylate ofhigh molecular weight, tripolyphosphates, pyrophosphates, and carbonateswhen such compositions are used at low ratios of builder to hardness Theinclusion of whiteness maintenance additives in detergent compositionsis a common practice and a number of such additives are known that do arelatively effective job. Among the whiteness maintenance additivessuggested for inclusion in a detergent composition arecarbbxymethylcellulose salts, sodium cellulose acetate sulfate, salts ofcellulose and starch sulfate, carboxyalkylcellulose, andhydroxyalkylcellulose. Various combinations of the noted compounds havealso been suggested as having utility in a detergent composition.

3,794,605 Patented Feb. 26, 1974 "Ice While the above known additivesperform satisfactorily, a whiteness maintenance additive mixture has nowbeen discovered that performs eminently Well when used in a builtdetergent composition. The novel mixture of this invention is especiallyuseful in detergent compositions built with polymaleate salts.

Accordingly, it is an object of this invention to improve the whitenessmaintenance values of detergent compositions.

It is another object of this invention to provide a new and improveddetergent whiteness maintenance additive which when included in a builtdetergent composition provides satisfactory whiteness maintenance.

It is still another object of this invention to provide a builtdetergent composition that is effective in maintaining the originalappearance of fabrics or like materials.

A still further object of this invention is to provide a built detergentcomposition that cleans satisfactorily and possesses satisfactorywhiteness maintenance values.

Another object of this invention is to formulate a polymaleate-builtdetergent composition possessing excellent whiteness maintenanceproperties.

These and other objects will become apparent from the description thatfollows.

SUMMARY OF THE INVENTION An effective detergent additive composition isprovided for preventing the redeposition of soil particles anddeposition of hardness ion-builder salts and hence improving thewhiteness maintenance value of laundered fabrics. The detergent additivecomposition consists essentially of a mixture of the water-soluble saltsof (a) a cellulose sulfate ester and (b) a copolymer of a vinyl compoundand maleic anhydride in a proportion of from 1:300 to 9:1, by weightrespectively. More particularly a built detergent composition embodyingthe present invention comprises a builder salt and a detergent selectedfrom the group consisting of anionic, nonionic, zwitterionic, andampholytic detergents in a builder to detergent weight ratio of from1:10 to 10:1 and from 0.1% to 20% of a mixture of cellulose sulfateester and a copolymer of a vinyl compound and maleic anhydride in aweight ratio of from 1:300 to 9:1, respectively.

DESCRIPTION OF THE INVENTION The present invention relates to a novelwhiteness maintenance additive and to built detergent compositionscontaining same.

The whiteness maintenance property of a built detergent composition asused herein refers to the ability of the detergent composition toprevent the redeposition of soil and the deposition of hardness ionbuilder salts onto laundered fabric-s, Both the aforementioned soil andhardness ion salts have an adverse effect on the appearance of washedfabrics. That is, fabrics washed with a built detergent compositionpossessing poor whiteness maintenance properties will after relativelyfew washes take on a greyish color. This change in color is attributedto a combination of redeposited soil and deposited hardness ion salts.

The whiteness maintenance additive of this invention consists of amixture of the water-soluble salts of a cellulose sulfate ester and acopolymer of a vinyl compound and maleic anhydride. Cellulose sulfateesters have been used as soil-suspending additives in detergentformulations previously. The water-soluble salt of a copolymer of avinyl compound and maleic anhydride has also been used in detergentcompositions previously. However, it was surprisingly discovered that amixture of the two compounds when used in a built detergent compositionimproves whiteness maintenance in a synergistic manner. That is, themixture of this invention in the ratio herein specified significantlyprovides a whiteness maintenance improvement in a built detergentcomposition over such a composition containing either component alone atthe same usage level.

The cellulose sulfate ester salts of this invention are known compounds.The cellulose sulfate ester salts used herein have a molecular weight offrom 15,000 to 1,000,000, preferably from 36,000 to 350,000 and a degreeof sulfate substitution of from 0.2 to 1.

A degree of sulfate substitution above 1 should be avoided sincedecreased soil antiredeposition is obtained. Similarly a degree ofsulfate substitution below 0.2 should be avoided because decreased soilantiredeposi-tion is obtained with such compounds. Preferably the degreeof sulfate substitution is from 0.3 to 0.8.

Examples of suitable cellulose sulfate esters are the water-solublesalts of cellulose acetate sulfate, cellulose sulfate,hydroxyethylcellulose sulfate, methylcellulose sulfate, andhydroxypropylcellulose sulfate. The degree of,

substitution of the nonionic substituent of the above com pounds, i.e.the acetate, hydroxymethyl, methyl, and hydroxypropyl substituents aswell as of other cellulose sulfate ester compounds ranges up to 2.5 andpreferably is from 0.5 to 2.2. The above list is a compilation ofsuitable cellulose sulfate esters that are used in this invention. Itshould not be taken as being all inclusive since others will be apparentto those skilled in the detergency art.

Examples of water-soluble cations that form the salts of the sulfateesters of this invention are the alkali metals, e.g. sodium andpotassium. Sodium is especially preferred. Other cations that aresuitable are ammonium and sub stitutcd ammonium compounds, such asmono-, di-, and trialkylammonium, mono-, di-, and triethylammonium,mono-, di-, and trimethylammonium and mono-, di-, andtriethanolammonium.

Of the cellulose sulfate esters that are used in this invention, sodiumcellulose acetate sulfate and sodium cellulose sulfate are mostpreferred.

The other necessary component of the mixture of this invention is awater-soluble salt of a copolymer of a vinyl compound and maleicanhydride. The vinyl compound is of the formula CH =CHY wherein Yrepresents a C alkyl ether radical. The cation that forms thewater-soluble salt for this copolymer is selected from the group ofcations listed above for the cellulose sulfate esters. These copolymercompounds have a molecular weight between 5,000 and 1,000,000,preferably between 10,000 and 350,000.

It has been found that a mixture of the Water-soluble salts of cellulosesulfate ester and a copolymer of the vinyl compound and maleic anhydridewhen employed in a built detergent composition in a minor amount, i.e.in an amount ranging from 0.1% to 20% of the total composition by weightprovides a very effective whiteness maintenance additive. Useage levelsbelow 0.1% are not noticeably effective. A useage level above 20% can beused but it provides no noticeable increase in whiteness maintenance.Preferably from 1% to 12% by weight of the total built detergentcomposition is the mixture of this invention.

Useful proportions for preparing the mixtures of the additives of thisinvention on a weight basis of cellulose sulfate ester to copolymer ofthe vinyl compound and maleic anhydride are from 1:300 to 9:1,preferably from 1:90 to 3:1. An ester to copolymer ratio of less than1:300 give unsatisfactory white maintenance results in that excess soilparticles are redeposited onto the textiles. An ester to copolymer ratiogreater than 9:1 also gives poorer whiteness maintenance results in thatexcessive hardness ion builder salts are free to deposit onto thetextiles.

The whiteness maintenance additive of this invention is embodied in abuilt detergent composition containing a water-soluble salt and adeter-gent in a builder salt to detergent weight ratio of from 1:10 to10:1. The built detergent composition has the following formulation:

(a) from 5% to of a water-soluble builder salt;

(b) from 5% to 60% of a detergent selected from the group consisting ofnonionic, anionic, zwitterionic, and ampholytic detergents; and

(c) from 0.1% to 20% of a mixture of the water-soluble salts of (a) acellulose sulfate ester and (b) a copolymer of a vinyl compound andmaleic anhydride as hereinbefore defined in a weight ratio of from 1:300to 9:1, respectively,

all by percent by weight of the total composition.

In a very preferred built detergent composition the Weight ratio ofbuilder salt to detergent is from 1:2 to 5:1.

Examples of builders and detergents useful in the present invention areset out below.

(A) Anionic soap and non-soap synthetic detergents This class ofdetergents includes ordinary alkali metal soaps such as the sodium,potassium, ammonium and alkylolammonium salts higher fatty acidscontaining from about 8 to about 24 carbon atoms and preferably fromabout 10 to about 20 carbon atoms. Suitable fatty acids can be obtainedfrom natural sources such as, for instance, from plant and animal esters(e.g., palm oil, coconut oil, babassu oil, soybean oil, castor oil,tallow, whale and fish oils, grease, lard, and mixtures thereof). Thefatty acids also can be synthetically prepared (e.g., by the oxidationof petroleum, or by hydrogenation of carbon monoxide by theFischer-Tropsch process). Resin acids are suitable such as rosin andthose resin acids in tall oil. Naphthenic acids are also suitable.Sodium and potassium soaps can be made by direct saponification of thefats and oils or by the neutralization of the free fatty acids which areprepared in a separate manufacturing process. Particularly useful arethe sodium and potassium salts of the mixtures of fatty acids derivedfrom coconut oil and tallow, i.e., sodium or potassium tallow andcoconut soap.

This class of detergents also includes water-soluble salts, particularlythe alkali metal salts of organic sulfuric reaction products having intheir molecular structure an alkyl radical containing from about 8 toabout 22 carbon atoms and a sulfonic acid or sulfuric acid esterradical. (Included in the term alkyl is the alkyl portion of higher acylradicals.) Examples of this group of synthetic detergents which form apart of the preferred built detergent compositions of the presentinvention are the sodium or potassium alkyl sulfates, especially thoseobtained by sulfating the higher alcohols (C -C carbon atoms) producedby reducing the glycerides of tallow or coconut oil; sodium or potassiumalkyl benzene sulfonates, in Which the alkyl group contains from about 9to 15 carbon atoms, in straight chain or branched chain configuration,e.g. those of the type described in United States Letters PatentsNumbers 2,220,099 and 2,477,383 (especially valuable are linear straightchain alkyl benzene sulfonates in which the average of the alkyl groupsis about 13 carbon atoms abbreviated hereinafter as C LAS); sodium alkylglyceryl ether sulfonates, especially those ethers of higher alcoholsderived from tallow and coconut oil; sodium coconut oil fatty acidmonoglyceride sulfonates and sulfates; sodium or potassium salts ofsulfuric acid esters of the reaction product of one mole of a higherfatty alcohol (e.g. tallow or coconut oil alcohols) and about 1 to 6moles of ethylene oxide; sodium or potassium salts of alkyl phenolethylene oxide ether sulfate with about 1 to about 10 units of ethyleneoxide per molecule and in which the alkyl radicals contain about 8 toabout 12 carbon atoms.

Anionic phosphate surfactants are also useful in the present invention.These are surface active materials having substantial detergentcapability in which the anionic solubilizing group connectinghydrophobic moieties is an oxy acid of phosphorus. The more commonsolubilizing groups, of course, are -SO H, -SO H, and -CO H. Alkylphosphate esters such as (RO') PO H and in which R represents an alkylchain containing from about 20 carbon atoms are useful.

These esters can be modified by including in the molecule from one toabout 40 alkylene oxide units, e.g., ethylene oxide units. Formulae forthese modified phosphate anionic detergents are in which R represents analkyl group containing from about 8 to 20 carbon atoms, or analkylphenyl group in which the alkyl group contains from about 8 to 20carbon atoms, and M represents a soluble cation such as hydrogen,sodium, potassium, ammonium or substituted ammonium; and in which n isan integer from 1 to about 40.

Another class of suitable anionic organic detergents particularly usefulin this invention includes salts of 2- acyloxy-alkane-l-sulfonic acids.These salts have the formula where R is alkyl of about 9 to about 23carbon atoms (forming with the two carbon atoms an alkane group);

R is alkyl of 1 to about 8 carbon atoms; and M is a salt-formingradical.

The salt-forming radical M in the hereinbefore described structuralformula is a water-solubilizing cation and can be for example, an alkalimetal cation (e.g. so dium, potassium, lithium), ammonium orsubstitutedammonium cation. Specific examples of substituted ammoniumcations include methyl-, dimethyl-, and trimethylammonium cations andquaternary ammonium cations such as tetramethyl-ammonium and dimethylpiperidinium cations and those derived from alkylamines such asethylamine, diethylamine, triethylamine, mixtures thereof, and the like.

Specific examples of B-acyloxy-alkane-l-sulfonates, or alternatively2-acyloxyalkane-l-sulfonates, utilizable herein to provide superiorcleaning levels under substantially neutral washing conditions includethe sodium salt of 2-acetoxy-tridecane-l-sulfonic acid; the potassiumsalt of 2-propi0nyloxy tetradecane-l-sulfonic acid; the lithium salt of2-butanoyloxy-tetradecane-l-sulfonic acid; the sodium salt of2-pentanoyloxy-pentadecane-l-sulfonic acid; the sodium salt of2-acetoxy-hexadecane-l-sulfonic acid; the potassium salt of2-octanoyloxy-tetradecane-1- sulfonic acid; the sodium salt of2-acetoxy-heptadecane-lsulfonic acid; the lithium salt of2-acetoxy-octadecane-1- sulfonic acid; the potassium salt of2-acetoxy-nonadecanel-sulfonic acid; the sodium salt of2-acetoxy-uncosane-1- sulfonic acid; the sodium salt of2-propionyloxy-docosanel-sulfonic acid; the isomers thereof.

Preferred fi-acyloxy-alkane-l-sulfonate salts therein are the alkalimetal salts of fl-acetoxy-alkane-l-sulfonic acids corresponding to theabove formula wherein R is an alkyl of about 12 to about 16 carbonatoms, these salts being preferred from the standpoints of theirexcellent cleaning properties and ready availability.

Typical examples of the above described fi-acetoxy alkanesulfonates aredescribed in the literature: Belgium Pat. 650,323 issued July 9, 1963,discloses the preparation of certain 2-acyloxy alkanesulfonic acids.Similarly, US.

Pat. 2,094,451 issued Sept. 28, 1937, to Guenther et al. and 2,086,215issued July 6, 1937 to De Groote disclose certain salts of ,B-acetoxyalkanesulfonic acids. These references are hereby incorporated byreference.

A preferred class of anionic organic detergents are the B-alkyloxyalkane sulfonates. These compounds have the following formula:

where R is a straight chain alkyl group having from 6 to 20 carbonatoms, R is a lower alkyl group having from 1 to 3 carbon atoms, and Mis a salt-forming radical hereinbefore described.

Specific examples of fl-alkyloxy alkane sulfonates or alternatively2-alkyloxy alkane 1 sulfonates, utilizable herein to provide superiorcleaning and whitening levels under household washing conditions includepotassium B-methoxydecanesulfonate, sodiumfi-methoxy-tridecanesulfonate, potassium fi-ethoxytetradecylsulfonate,sodium p-isopropoxyhexadecylsulfonate, lithiumfi-t-butoxytetradecylsulfonate, sodium ,8-methoxyoctadecylsulfonate, andammonium B-n-propoxydodecylsulfonate.

Other synthetic anionic detergents useful herein are alkyl ethersulfates. These materials have the formula RO(C H O) SO' M wherein R isalkyl or alkenyl of about 10 to about 20 carbon atoms, x is 1 to 30, andMis a salt-forming cation defined hereinbefore.

The alkyl ether sulfates of the present invention are condensationproducts of ethylene oxide and monohydric alcohols having about 10 toabout 20 carbon atoms. Preferably, R has 14 to 18 carbon atoms. Thealcohols can be derived from fats, e.g., coconut oil or tallow, or canbe synthetic. Lauryl alcohol and straight chain alcohols derived fromtallow are preferred herein. Such alcohols are reacted with 1 to 30, andespecially 6, molar proportions of ethylene oxide and the resultingmixture of molecular species, having, for example, an average of 6 molesof ethylene oxide per mole of alcohol, is sulfated and neutralized.

Specific examples of alkyl ether sulfates of the present invention aresodium coconut alkyl ethylene glycol ether sulfate; lithium tallow alkyltriethylene glycol ether sulfate; and sodium tallow alkylhexaoxyethylene sulfate.

Preferred herein for reasons of excellent cleaning properties and readyavailability are the alkali metal coconutand tallow-alkyl oxyethyleneether sulfates having an average of about 1 to about 10 oxyethylenemoieties. The alkyl ether sulfates of the present invention are knowncompounds and are described in US. Pat. 3,332,- 876 to Walker (July 25,1967) incorporated herein by reference.

Additional examples of anionic non-soap synthetic detergents which comewithin the terms of the present invention are the reaction products offatty acids esterified with isethionic acid and neutralized with sodiumhydroxide where, for example, the fatty acids are derived from coconutoil; sodium or potassium salts of fatty acid amide of methyl tauride inwhich the fatty acids, for example, are derived from coconut oil. Otheran ionic synthetic detergents of this variety are set forth in UnitedStates Letters Pats. 2,486,921; 2,486,922; and 2,396,278.

Additional examples of anionic, non-soap, synthetic detergents, whichcome within the terms of the present invention, are the compounds whichcontain two anionic functional groups. These are referred to asdi-anionic detergents. Suitable di-anionic detergents are thedisulfonates, disulfates, or mixtures thereof which may be representedby the following formulae:

where R is an acyclic aliphatic hydrocarbyl group having 15 to 20 carbonatoms and M is a water-solubilizing cation, for example, the C to Cdisodium 1,2-alkyldisulfates, C to C dipotassium-1,2-alkyldisulfonatesor disulfates, disodium 1,9-hexadecy1 disulfates, C to Cdisodium-1,2-alkyldisulfonates, disodium 1,9-stearydisulfates and6,10-octaecyldisulfates.

The aliphatic portion of the disulfates or disulfonates is generallysubstantially linear, desirable, among other reasons, because it impartsdesirable biodegradable properties to the detergent compound.

The water-solubilizing cations include the customary cations known inthe detergent art, i.e., the alkali metals, and the alkaline earthmetals, as well as other metals in group H-A, II-B, IIIA, IV-A and IV-Bof the Periodic Table except for boron. The preferred water-solubilizingcations are sodium or potassium. These dianionic detergents are morefully described in British Letters Pat. 1,151,392 which claims priorityon an application made in the United States of America (No. 564,556) onJuly 12, 1966.

Additional examples of anionic non-soap synthetic detergents which comewithin the terms of the present invention are the reaction product offatty acids esterified with isethionic acid and neutralized with sodiumhydroxide where, for example, the fatty acids are derived from coconutoil; sodium or potassium salts of fatty acid amide of methyl tauride inwhich the fatty acids, for example, are derived from coconut oil. Otheranionic synthetic detergents of this variety are set forth in UnitedStates Letters Pats. 2,486,921, 2,486,922; and 2,396,278.

Still other anionic synthetic detergents include the class designated assuccinamates. This class includes such surface active agents as disodiumN-octadecylsulfo succinamate; tetrasodium N-(l,2-dicarboxyethyl) Noctadecyl-sulfo-succinamate; diamyl ester of sodium sulfosuccinic acid;dihexyl ester of sodium sulfosuceinic acid; dioctyl ester of sodiumsulfosuccinic acid.

Other suitable anionic detergents utilizable herein are olefinsulfonates having about 12 to about 24 carbon atoms. The term olefinsulfonates is used herein to mean compounds which can be produced by thesulfonation of u-olefin by means of uncomplexed sulfur trioxide,followed by neutralization of the acid reaction mixture in conditionssuch that any sultones which have been formed in the reaction arehydrolyzed to give the corresponding hydroxy-alkanesulfonates. Thesulfur trioxide may be liquid or gaseous, and is usually, but notnecessarily, diluted by inert diluents, for example by liquid Schlorinated hydrocarbon, etc., when used in the liquid form, or by air,nitrogen, gaseous S0 etc., when used in the gaseous form.

The a-Olefins from which the olefin sulfonates are derived aremono-olefins having 12 to 24 carbon atoms, preferably 14 to 16 carbonatoms. Preferably, they are straight chain olefins. Examples of suitablel-olefins include l-dodecene; l-tetradecene; l-hexadecene; l-octadecene;l-eicosene and l-tetracosene.

In addition to the true alkene sulfonates and a proportion ofhydroxy-alkanesulfonates, the olefin sulfonates can contain minoramounts of other materials, such as alkene disulfonates depending uponthe reaction conditions, proportions of reactants, the nature of thestarting olefins and impurities in the olefin stock and side reactionsduring the sulfonation process.

A specific anionic detergent which has also been found excellent for usein the present invention is described more fully in the US. Pat.3,332,880 of Phillip F. Pfiaumer and Adriaan Kessler, issued July 25,1967, titled Detergent Composition, the disclosure of which is hereinincorporated by reference.

(B) Nonionic synthetic detergents Nonionic synthetic detergents may bebroadly defined as compounds produced by the condensation of alkylene 8oxide groups (hydrophilic in nature) with an organic hydrophobiccompound, which may be aliphatic or alkyl aromatic in nature. The lengthof the hydrophilic or polyoxyalkylene radical which is condensed withany particular hydrophobic group can be readily adjusted to yield awater-soluble compound having the desired degree of balance betweenhydrophilic and hydrophobic elements.

For example, a well known class of nonionic synthetic detergents is madeavailable on the market under the trade name of Pluronic. Thesecompounds are formed by condensing ethylene oxide with a hydrophobicbase formed by the condensation of propylene oxide with propyleneglycol. The hydrophobic portion of the molecule which, of course,exhibits water insolubility, has a molecular weight of from about 1500to 1800. The addition of polyoxyethylene radicals to this hydrophobicportion tends to increase the water solubility of the molecule as awhole and the liquid character of the product is retained up to thepoint where polyoxyethylene content is about of the total weight of thecondensation product.

Other suitable nonionic synthetic detergents include:

(1) The polyethylene oxide condensates of alkyl phenols, e.g., thecondensation products of alkyl phenols having an alkyl group containingfrom about 6 to 12 carbon atoms in either a straight chain or branchedchain configuration, with ethylene oxide, the said ethylene oxide beingpresent in amounts equal to 5 to 25 moles of ethylene oxide per mole ofalkyl phenol. The alkyl substituent in such compounds may be derivedfrom polymerized propylene, diisobutylene, octene, or nonene, forexample.

(2) Those derived from the condensation of ethylene oxide with theproduct resulting from the reaction of propylene oxide and ethylenediamine. For example, compounds containing from about 40% to aboutpolyoxyethylene by weight and having a molecular weight of from about5,000 to about 11,000 resulting from the reaction of ethylene oxidegroups with a hydrophobic base constituted of the reaction product ofethylene diamine and excess propylene oxide, said base having amolecular weight of the order of 2,500 and 3,000, are satisfactory.

(3) The condensation product of aliphatic alcohols having from 8 to 22carbon atoms, in either straight chain or branched chain configuration,with ethylene oxide, e.g., a coconut alcohol-ethylene oxide condensatehaving from 5 to 30 moles of ethylene oxide per mole of coconut alcohol,the coconut alcohol fraction having from 10 to 14 carbon atoms.

(4) Nonionic detergents include nonyl phenol condensed with either about10 or about 30 moles of ethylene oxide per mole of phenol and thecondensation products of coconut alcohol with an average of either about5.5 or about 15 moles of ethylene oxide per mole of alcohol and thecondensation product of about 15 moles of ethylene oxide with one moleof tridecanol.

Other examples include dodecylphenol condensed with 12 moles of ethyleneoxide per mole of phenol; dinonylphenol condensed with 15 moles ofethylene oxide per mole of phenol; dodecyl mercaptan condensed with 10moles of ethylene oxide per mole of mercaptan; bis-(N-2- hydroxyethyl)lauramid; nonyl phenol condensed with 20 moles of ethylene oxide permole of nonyl phenol; myristyl alcohol condensed with 10 moles ofethylene oxide per mole of myristyl alcohol; lauramide condensed with 15moles of ethylene oxide per mole of lauramide; and di-isooctylphenolcondensed with 15 moles of ethylene oxide.

(5) A detergent having the formula R R R N- O (amine oxide detergent)wherein R is an alkyl group containing from about 10 to about 28 carbonatoms, from 0 to about 2 hydroxy groups and from 0 to about 5 etherlinkages, there being at least one moiety of R which is an alkyl groupcontaining from about 10 to about 18 carbon atoms and 0 other linkages,and each R and R are selected from the group consisting of alkylradicals and hydroxyalkyl radicals containing from 1 to about 3 carbonatoms;

Specific examples, of amine oxide detergents include:dimethyldodecylamine oxide, dimethyltetradecylamine oxide,ethylmethyltetradecylamine oxide, cetyldimethylamine oxide,dimethylstearylamine oxide, cetylethylpropylamine oxide,diethyldodecylamine oxide, diethyltetradecylamine oxide,dipropyldodecylamine oxide, bis-(2-hydroxyethyl) dodecylamine oxide,bis-(2-hydroxyethyl)-3-dodecoxyl-lhydroxypropylamine oxide, (2hydroxypropyl)methyltetradecylamine oxide, dirnethyloleyamine oxide,dimethyl-(2-hydroxydodecyl)amine oxide, and the corresponding decyl,hexadecyl and octadecyl homologs of the above compounds.

(6) A detergent having the formula R R R P O (phosphine oxide detergent)wherein R is an alkyl group containing from about 10 to about 28 carbonatoms, from to about 2 hydroxy groups and from 0 to about 5 etherlinkages, there being at least one moiety of R which is an alkyl groupcontaining from about to about 18 carbon atoms and O ether linkages, andeach of R and R are selected from the group consisting of alkyl radicalsand hydroxyalkyl radicals containing from 1 to about 3 carbon atoms.

Specific examples of the phosphine oxide detergents include:dimethyldodecylphosphine oxide, dimethyltetradecylphosphine oxide,ethylmethyltetradecylphosphine oxide, cetyldirnethylphosphine oxide,dimethylstearylphosphine oxide, cetylethylpropylphosphine oxide,diethyldodecylphosphine oxide, diethyltetradecylphosphine oxide,dipropyldodecylphosphine oxide, bis (hydroxymethyl)dodecylphosphineoxide, bis-(2-hydroxyethyl)dodecylphosphine oxide, (2hydroxypropyl)methyltetradecylphosphine oxide, dimethyloleylphosphineoxide, and dimethyl-(2-hydroxydodecyl)phosphine oxide and thecorresponding decyl, hexadecyl, and octadecyl homologsof the abovecompounds.

(7) A detergent having the formula 0 E i-R (sulfoxide detergent) whereinR is an alkyl radical containing from about 10 to about 28 carbon atoms,from 0 to about 5 ether linkages and from 0 to about 2 hydoxysubstituents at least one moiety of R being an alkyl radical containing0 ether linkages and containing from about 10 to about 18 can-bon atoms,and wherein R is an alkyl radical containing from 1 to 3 carbon atomsand from one to two hydroxyl groups: octadecyl methyl sulfoxide, dodecylmethyl sulfoxide, tetradecyl methyl sulfoxide, 3-hydroxytridecyl methylsulfoxide, 3-methoxytridecyl methyl sulfoxide, 3-hydroxy-4-dodecoxybutylmethyl sulfoxide, octadecyl 2-hydroxyethyl sulfoxide, dodecylethylsulfoxide.

(C) Ampholytic synthetic detergents Ampholytic synthetic detergents canbe broadly described as derivatives of aliphatic or aliphaticderivatives of heterocyclic secondary and tertiary amines, in which thealiphatic radical may be straight chain or branched and wherein one ofthe aliphatic substituents contains from about 8 to 18 carbon atoms andat least One contains an anionic water-solubilizing group, e.g.,carboxy, sulfo, sulfato.

Examples of compounds falling within this definition are:

sodium-3- (dodecylamino -propionate,

sodium 3-(dodecylamino)propane-l-sulfonate,

sodium 2-(dodecylamino)ethyl sulfate,

sodium 2-(dimethylamino)octadecanoate,

disodium 3-(N-carboxymethyldodecylamino)-propanel-sulfonate, I

disodium octadecyl-iminodiacetate,

sodium 1-carboxymethyl-2-undecylimidazole, and

sodium N,N-bis(2-hydroxyethyl-2-sulfato-3-dodecoxypropylamine.

(D) Zwitterionic synthetic detergents Zwitterionic synthetic detergentscan be broadly described as derivatives of alphatic quaternary ammoniumand phosphonium or tertiary sulfonium compounds, in which the cationicatom may be part of a heterocyclic ring, and in which the aliphaticradical may be straight chain or branched, and wherein one of thealiphatic substituents contains from about 3 to 18 carbon atoms, and atleast one aliphatic substituent contains an anionic water-solubilizinggroup, e.g., carboxy, sulfo, sulfato, phosphato, or phosphono. Examplesof compounds falling within this definition are:

3- (N,N-dimethyl-N-hexadecyl-ammonio) 2-hydroxypropanel-sulfonate,

3-(N,N-dimethyl-N-hexadecylammonio)propane-1- sulfonate,

2- (N,N-dimethylN-dodecylammonio) acetate,

3- (N,N-dimethyl N-dodecylammonio propionate,

2- N,N-dimethyl-N-octadecylammonio ethyl sulfate,

2- (trimethylammonio ethyl dedecylphosphonate,

ethyl 3- N,N-dimethyl-N- do decylammonio propylphosphonate,

3- (P,P-dimethyl-P-dodecylphosphonio)propane-1- sulfonate,

2- (S-methyl-S-tert-hcxadecyl-sulfonio ethanel-sulfonate,

3- S-methyl-Sdodecylsulfonio) propionate,

sodium 2- N,N-dimethyl-N-dodecylammonio) ethyl phosphonate, I

4- S-methyl-S-tetradecylsulfonio butyrate,

1- 2-hydroxyethyl -2-undecylimidazoliuml-acetate,

2- (trimethylammonio octadecanoate, and

3-(N,N-bis- (2-hydroxyethy1)-N-octadecylammonio)-2-hydroxypropane-1-sulfonate.

Some of these detergents are described in the following U.S. patents:2,129,264; 2,178,353; 2,774,786; 2,813,898; and 2,828,332.

Examples of suitable water-soluble, inorganic alkaline detergencybuilder salts are alkali metal carbonates, b0- rates, phosphates,polyphosphates, bicarbonates, silicates and sulfates. Specific examplesof such salts are sodium and potassium tetraborates, perborates,bicarbonates, carbonates, tripolyphosphates, pyrophosphates,orthophosphates and hexametaphosphates.

Examples of suitable organic alkaline detergency builder salts are: (l)Water-soluble salts of phytic acid, e.g., sodium and potassiumphytatessee U.S. Pat. 2,739,942; (2) water-soluble, polyphosplronates,including specifically, sodium, potassium and lithium salts of ethane-1-hydroxy-l, l-diphosphonic acid, sodium, potassium and lithium salts ofmethylene diphosphonic acid, sodium, potassium and lithium salts ofethylene diphosphonic acid, and sodium, potassium and lithium salts ofethane-1,1,2-

triphosphonic acid. Other examples include the alkali metal salts ofethane-Z-carboxy-l,l-diphosphonic acid, hydroxymethanediphosphonic acid,carbonyldiphosphonic acid, ethane-l-hydroxy-1,1,2-triphosphonic acid,ethane-2- hydroxy-l,1,2-triphosphonic acid,propane-l,l,3,3-tetraphosphonic acid, propane-1,l,2,3-tetraphosphonicacid, and propane-1,2,2,3-tetraphosphonic acid; (3) water-soluble saltsof polycarboxylate polymers and copolymers as described in U.S. Pat. No.3,308,067. Specifically, a detergent builder material comprising awater-soluble salt of a polymeric aliphatic polycarboxylic acid havingthe following structural relationships as to the position of thecarboxylate groups and possessing the following prescribed physicalcharacteristics: (a) a minimum molecular weight of about 350 calculatedas to the acid form; (b) an equivalent Weight of about 50 to aboutcalculated as to acid form; (c) at least 45 mole percent of themonomeric species having at least two carboxyl radicals separated fromeach other by not more than two carbon atoms; (d) the site of attachmentof the polymer chain of any car boxyl-containing radical being separatedby not more than three carbon atoms along the polymer chain from thesite of attachment of the next carboxyl-containing radical. Specificexamples are polymers of itaconic acid, aconitic acid, maleic acid,mesaconic acid, fumaric acid, methylene malonic acid, and citraconicacid and copolymers with themselves and other compatible monomers suchas ethylene; (4) Water-soluble salts of polycarboxylate polymers notincluded in (3) such as polyacrylates, polyisobutylene/ maleates, andpolyacrylamide/acrylates; (5) water-soluble salts of polycarboxylates asdescribed in US. Pats. 2,264,103 and 2,311,008; and (6) mixturesthereof.

Mixtures of organic and/or inorganic builders can be used and aregenerally desirable. One such mixture of builder-s is disclosed in US.Pat. 3,392,121, e.g., ternary mixtures of sodium tripolyphosphate,sodium nitrilotriacetate and trisodium ethane-l-hydroxy-l,l-diphosphomate. The above described builders can also be utilizedsingly in this invention.

In addition, other builders can be used satisfactorily such aswater-soluble salts of mellitic acid, citric acid, pyromellitic acid,benzene pentacarboxylic acid, oxydiacetic acid, oxydissuccinic acid.

The builders preferably employed with the whiteness maintenance additiveof this invention are the polymaleates having a molecular weight of from350 to 600,000 preferably from 450 to 60,000, tripolyphosphates,pyrophosphates and carbonates. The water-soluble salts of the abovepolymaleates are most preferred.

The finished detergent formulation of this invention can also haveincluded therein minor amounts of materials often included in detergentcomposition. Examples of such additives are tarnish inhibitors such asbenzotriazole or ethylene thiourea, fluorescers, perfumes, coloringmatter, enzymes, brightening agents, and bleaching agents.

The examples to follow are given to illustrate the invention. Unlessotherwise indicated all percentages are by weight on a dry basis.

The detergent additive compositions of this invention were tested forwhiteness maintenance by the following test procedures. A standardTergotometer tub, Model 7243, was filled with 1 liter 140 F. waterhaving a calcium hardness content of 7 grain/ gal. A built detergentcomposition was then added to the Tergotometer. The pH of this solutionwas next adjusted to 10.5. Thereafter a simulated soil component wasadded. This simulated soil comprised olive oil, oleic acid, mineral oiland air-borne soil components removed from the filter of anair-conditioning unit. The resulting mixture was then agitated for twominutes at a speed of 80 cycles per minute. After the above two minutesof agitation five 6" x 6" cotton terry cloths were added and washed forabout 10 minutes. The washed cloths were then rinsed in 1 liter of 7grain water for two minutes, run through a clothes wringer, rinsed asecond time in 1 liter of 7 grain water for two minutes and again runthrough a clothes wringer. They were then tumble-dried. This procedurewas repeated three times to give a total of four washings after whichthe terry cloths were graded.

The grading of the terry cloths for whiteness maintenance was done byway of two testsa test that recorded a whiteness value and a test thatmeasured calcium salt deposition. The test that measured the amount ofcalcium salt deposited on the terry cloths was done by means of x-rayspectroscopy. The results obtained were in terms of parts per million(p.p.m.) of calcium deposited. The

greater the amount of calcium salt deposited, the greater was theadverse effect on the loss in whiteness maintenance of the washedcloths.

The other test used to measure the whiteness maintenance property of thecompositions of this invention employed a Hunter color and colordifference meter (Model D25, manufactured by Hunter Associates Labs,Inc.). This instrument numerically measures the degree of lightness andred-green and yellow-blue tints in the cloths on three different scales,namely the L, a, and b scale, respectively. The readings so obtainedwere converted into a whiteness value by means of the formula Thegreater the value of W, the greater the degree of whiteness maintenance.As use herein the values were obtained using five thicknesses of clothsand a ceramic tile (Suntile #54, whiteness=86.2) as backing for theterry cloths. The cloths being measured were placed on the top of theaforementioned five thicknesses prior to obtaining any readings. Thiswas done to prevent the Suntile backing from affecting the readings.

The above two tests are necessary to fully evaluate the whitenessmaintenance effect exhibited by the compositions of this invention. Thewhiteness value obtained from the Hunter color and color differencemeter above is not a sufiicient measure of the total deposited materialon the cloth. In part, this is because the values obtained from it donot fully reflect the effect of the calcium deposition on the clothssince the calcium salts themselves in most cases are of a white shade.Thus, increased deposition of calcium on the cloths can counteract thegreying effect of soil and materially aflect the values obtained fromthe Hunter color and color diflierence meter. Similarly, the measure ofthe amount of calcium deposited on the cloths alone is not a goodmeasure of the whiteness maintenance property of the compositions ofthis invention since it does not reflect the amount of other componentsthat is deposited along with water-insoluble calcium salts. These othercomponents, i.e. redeposited soil affect the whiteness maintenance ofthe total detergent composition. However, results obtained from both ofthe aforementioned two tests when interpreted together accuratelyreflect the superior whiteness maintenance property of the compositionsof this invention.

EXAMPLE I The tables labelled Calcium Deposition and Whiteness listvalues obtained from the respective tests. Wash solutions containing thebuilder sodium polymaleate (NaPMA) at concentrations of 0.012%, 0.020%,0.024%, 0.028%, 0.032%, 0.036% and 0.060% were used for purposes ofthese tests. The NaPMA had an average molecular weight of 5000. Alsoincluded in each wash solution was 0.03% of the detergent sodium linearalkyl benzene sulfonate (LAS) with an average chain length of 11.4carbon atoms. The second through fifth columns list the amount of sodiumcellulose acetate sulfate (SCAS) of average molecular weight of about100,000, degree of acetyl substitution of 2.0 and degree of sulfatesubstitution of 0.56 and/or the amount of the sodium salt of hydrolyzedpoly(vinyl methylether/maleic anhydride) (PVMEM) of average molecularweight: 138,500 in parts per million (p.p.m.) of wash solution.

The above listed values for the whiteness readings obtained from theHunter color and color difference meter indicate that over a widepercentage range of builder/detergent/SCAS compositions, the whitenessvalues were greater than the same values obtained from a builder/detergent, i.e. SCAS-free composition. For example, at a NaPMAconcentration of 0.020% the builder/detergent/ SCAS composition had awhiteness value of 92.9, while the builder/detergent composition had asignificantly lower whiteness value of 92.2. This indicates that theSCAS does improve the appearance of the cloths washed with a detergentcomposition containing it. However, the calcium deposition testindicates that the same builder/ detergent/SCAS composition generallycauses a greater amount of calcium salt to be deposited on the clothsthan the SCAS-free compositions. Thus, at the same NaPMA concentrationof 0.020%, the builder/detergent/ SCAS composition had a calciumdeposition value of 690, significantly higher than the calciumdeposition value of 620 obtained for the builder/detergent composition.As a result of this calcium salt deposition, the washed cloths began totake on a greyish appearance due to the deposited calcium salts andsoil. The greyish appearance becomes more noticeable as the number ofwashings increases. Interpretation of the above test results indicatethat while the addition of SCAS to a built detergent compositionimproves the whiteness value obtained from cloths washed therewith, itdoes not decrease or prevent the deposition of calcium salts.Consequently the overall effect is that the whiteness maintenance of abuilder/detergent/SCAS composition is not fully satisfactory.

Comparison of the builder/detergent/PVMEM composition andbuilder/detergent compositions also indicate that the addition of PVMEMto a builder and detergent does not fully satisfactorily improve thecomposition with respect to whiteness maintenance. As can be seen fromthe above tables the PVMEM-containing compositions found in the fourthcolumn of the Calcium Deposition Table did have less deposition ofcalcium salts on the terry cloths than did the builder/ detergentcompositions. However, the whiteness values showed that thePVMEM-containing compositions of the fourth column exhibited lesservalues than the builder and detergent only compositions. Thus, overall,the addition of the PVMEM only to the builder and detergent compositionsdid not satisfactorily improve fully the built detergent composition.

The compositions of this invention, however, i.e. the compositionsrepresented in the last column perform better with respect to havingless calcium salts deposited on the cloths and improved or, in somecases, maintained the whiteness values, over compositions containing noSCAS and PVMEM. Accordingly, based on the favorable results of both thecalcium deposition and whiteness tests, the overall whitenessmaintenance of a built detergent composition is significantly improvedby the addi- 'tion thereto of the SCAS and PVMEM.

EXAMPLE II The following tests were run to show the synergetic resultsobtained from built detergent compositions containing a wide range ofmixtures of cellulose sulfate ester and copolymers of a vinyl compoundand maleic anhydride. The sodium cellulose sulfate had an averagemolecular weight of about 92,400 a degree of sulfate substitution of0.35. The copolymer used in this example was the same copolymer as usedin Example I.

The same test procedures and wash procedures described in Example I wereused in this example. The table below lists the ratio ofpoly(vinylmethylether/maleic anhydride) (PVMEM) to sodium cellulosesulfate (SCS) in the first column and the percentage of built detergentcomposition that is made up of the PVMEM-SCS mixture is in the secondcolumn. The remaining part of the compositions consists of the PMA andLAS described in Example I at a PMA to LAS who of 4.5.

(PVMEM Calcium PVMEM: plus SOS) deposition SCS ratio percent; (p.p.m.)whiteness The above results show that the compositions of thisinvention, i.e. B, C, D, E and F all had relatively low calciumdeposition values and high whiteness values. The net effect of thesetests showed that the whiteness maintenance of the compositions of thisinvention were satisfactory.

While Composition G of the above tests exhibited results that are notsubstantially different from Composition B, it should be realized thatthe above values were based on samples washed only four times.Significantly more dramatic results are obtained as the number of washesis increased. The example immediately below illustrates the increasinglygreater advantages of the present invention as the number of Washesincreases.

EXAMPLE III This example shows the effect the number of washings has onthe performance of a detergent composition. Two compositions weretested. Composition A falling within the ranges of this invention andComposition B falling outside the ranges. From the calcium depositon andwhiteness values listed in the tables, it is apparent that the greaterthe number of washes, the greater was the amount of calcium saltdeposited and the greater was the decrease in whiteness value. Thus, itcan be seen in regard to Examples I and II that what at first may appearto be a small performance difference actually is very significant andbecomes increasingly more important at the end of each successive set ofwashes. It also can be seen that the composition of this invention, i.e.Composition A exceeded the performance of Composition B after eachWashing.

The washing and grading procedures used in this example were the same asused in Example I. The following composition were used Composition APercent Sodium polymaleate (average molecular weight 15 Composition BPercent Sodium polymaleate (average molecular weight Sodium linear alkylbenzene sulfonate (average alkyl chain length=11.4) 50.8Poly(vinylrnethylether/maleic anhydride (average molecularweight=138,500)

The ratio of the polymaleate and alkyl benzene sulfonate of the abovecompositions were included in each formulation at the same relativeproportion. The same polymaleate/alkyl benzene sulfonate concentrationin the wash solutions were used in this example as in Example I, i.e.0.024%.

examples are illustrative of the present The following invention.

EXAMPLE V Parts Poly(vinylmethylether/maleic anhydride) (averagemolecular wt. 1,000,000) 200 Sodium cellulose sulfate (averagemolecular. wt.

=350,000 and degree of sulfate substitution: 1) 1 Sodium hydroxyethylcellulose sulfate (average molecular Wt.=l,000,000 and degrees ofsulfate and hydroxyethyl substitution=0.8 and 2.5, respectively) 1EXAMPLE VIII Parts Poly(vinylmethylether/maleic anhydride) (averagemolecular weight=700,000) 1 Sodium cellulose sulfate (average molecularwt.

=600,000 and sulfate degree of substitution=0.5) 9

The detergent additive compositions of Examples IV through VIII can beusefully included in detergent compositions of any form, includingsolid, powder, granular, and liquid fmmlllations.

16 EXAMPLE IX Percent Poly(vinylethylether/maleic anhydride) (averagemolecular wt. ==5,000) Sodium methyl cellulose sulfate (average degreeof sulfate and methyl substitution:0.2 and 2.5, respectively andmolecular Wt.=l,000,000) 0.01 Sodium tripolyphosphate 60.0 Condensationproduct of 1 mole of tallow alcohol and 3 moles of ethylene oxide 6.0Sodium sulfate 23.0 Sodium silicate 5.0 Water 2.99

EXAMPLE X Percent Poly(vinylbutylether/maleic anhydride) (averagemolecular wt.= 1,000,000) Sodium cellulose acetate sulfate (avg. sulfateand acetyl degree of substitution=0.4 and 0.5 respectively. Molecularwt.-=15,000) 10.8

Hexasodium salt of benzene hexacarboxylic acid 50.0

Sodium tallow soap 11.0 Sodium sulfate 17.0 Sodium silicate 7.0 Water3.0

EXAMPLE XI Percent Poly (vinylrnethylether/maleic anhydride) (averagemolecular wt.=10,000) 0.080

Sodium hydroxyethyl cellulose sulfate (average degree of sulfate andhydroxethyl substitution :10, and 1.2, respectively and molecular wt.

=350,000) 0.020 Sodium polymaleate (average molecular wt.

:350) 5.0 Sodium beta-methoxy hexadecane sulfonate 50.0 Sodium sulfate35.0 Water 9.9

What is claimed is:

1. A granular built detergent composition, consisting essentially of:

(a) from 5% to by weight of a water-soluble detergency builder salt;

(b) from 5% to 60% by Weight of a detergent selected from the groupconsisting of non-ionic, anionic, zwitterionic and ampholytic detergent;and

(c) from 0.1% to 20% by Weight of a mixture of the water-soluble saltsof (i) a cellulose sulfate ester selected from the group consisting ofcellulose acetate sulfate, cellulose sulfate, hydroxyethylcellulosesulfate, methylcellulose sulfate and hydroxypropylcellulose sulfate; and(ii) a copolymer of a vinyl compound of the formula CH =CHY, wherein Yrepresents a C alkyl ether radical, and maleic anhydride, in a weightratio of cellulose ester to copolymer of from 1:300 to 9:1.

2. The built detergent composition of claim 1 wherein the weight ratioof cellulose ester to copolymer is from 1:90 to 3:1.

3. The built detergent composition of claim 1 wherein the mixture of thewater-soluble salt of the cellulose ester and the copolymer of the vinylcompound and maleic anhydride is present in the composition in an amountof from 1% to 12% by weight of the total composition.

4. The built detergent composition of claim 1 wherein the copolymer hasan average molecular weight of from 5,000 to 1,000,000.

5. The built detergent composition of claim 1 wherein the celluloseester has a degree of sulfate substitution of from 0.2 to 1 and has anaverage molecular weight of from 15,000 to 1,000,000.

6. The built detergent composition of claim 1 wherein the celluloseester has a nonionic substituent and. wherein 17 the degree ofsubstitution of the nonionic substituent ranges up to 2.5.

7. The built detergent composition of claim 1 wherein the celluloseester is sodium cellulose sulfate and wherein the copolymer ispoly(vinylmethylether/maleic anhydride).

8. The built detergent composition of claim 1 wherein the celluloseester is sodium cellulose acetate sulfate and wherein the copolymer ispoly(vinylmethylether/maleic anhydride).

9. The built detergent composition of claim 1 wherein the water-solubledetergency builder salt and detergent are co-present in a buildersalt-to-detergent weight ratio of from 1:10 to 10:1.

10. The built detergent composition of claim 1 wherein the water-solublesalt is a salt of polymaleic acid having an average molecular weight offrom 350 to 600,000.

18 References Cited UNITED STATES PATENTS 3,254,028 5/1966 Wixon 252Dig.15 3,144,412 8/1964 Inamorato 252Dig. 15 3,211,660 10/1965 Marion et al.252Dig. 15 3,308,067 3/1969 Diehl 252Dig. 15 3,485,762 12/1969 Gower etal 252Dig. 15 3,235,505 2/1966 Turell 25289 FOREIGN PATENTS 545,1268/1957 Canada 252Dig. 15

WILLIAM E. SCI-I'ULZ, Primary Examiner U.S. C1. X.R. 252Digest 15

